In a semiconductor processing equipment such as a batch-type vertical apparatus for performing a diffusion or a CVD process, semiconductor wafers are loaded into and unloaded from the apparatus while being kept in cassettes. Two kinds of carriers have been conventionally used. One is a box-shaped cassette having a pair of openings on two opposite sides and the other is a box-shaped FOUP (front opening unified pod; hereinafter, pod) having an opening on one side thereof with a pod door removably mounted thereon.
In the semiconductor processing equipment using the pod as the carrier, the wafers can be kept protected from contaminations of ambient atmosphere while being transferred since the pod containing the wafers is airtightly closed. Accordingly, the degree of cleanliness required for a clean room of the semiconductor processing equipment may be lowered, which in turn reduces cost for the maintenance of the clean room. For such reasons, the pod is gaining popularity as the carrier in the semiconductor processing equipment recently.
The semiconductor processing equipment using the pod as the wafer carrier is provided with a pod door opener for remaining and restoring the pod door. One example of such conventional pod door opener is disclosed in U.S. Pat. No. 5,772,386, wherein the pod door opener is disposed on a wafer loading port and equipped with a closure capable of frictionally engaging with a door of the pod located on the wafer loading port. The pod can be uncovered by lowering down the closure while the closure engages with the door.
However, since the conventional semiconductor processing equipment is provided with only a single wafer loading port, the lead time required in preparing wafers for an actual process increases due to replacement of a pod on the wafer loading port with another, which in turn lengthens the overall processing time of the semiconductor manufacturing process, thereby reducing the throughput thereof.
Another equipment having a multi-stage pod door system is disclosed in U.S. Pat. No. 6,042,324. Since, however, the pod doors of the equipment are simultaneously opened as a single unit by a vertical actuator, the lead time may not be reduced and the height of the equipment increases.